I have a DOHC black top ZC and I have the ECU that matches this motor. Mi Problema is that below about 2800 RPM while driving it feels like my car is miss firing badly, it sounds like it's only running on 3 cylinders. I got the Black top ECU and I thought that would fix it, I tried advancing the timing, Ive replace the TPS, the IAC, New ZC Dizzy, I've changed spark plugs and spark plug wires, I even got the wires for the motor the exact part number for a ZC shipped from Japan and it still does it. so if any one has any suggestions it would be much appreciated.